The primary objective of this research project is to define the relation of insulin resistance to blood pressure in children and to changes in blood pressure that occur during adolescence. If insulin resistance is related etiologically to hypertension, it should predate the appearance of elevated blood pressure or it should increase coincident with a rise in blood pressure in individuals tracking toward hypertensive blood pressure levels. The specific aims for this proposal are: 1) to conduct blood pressure screening of 11,500 5th-8th grade (11-15 years old) Minneapolis school children to develop a blood pressure distribution for recruitment of an enriched study population of 50% of the distribution and 50% randomly selected from the remaining 85% of the distribution; 2) to obtain baseline measurements of blood pressure; anthropometric measurements; fasting serum insulin, glucose and lipids; measures of insulin resistance; forearm vascular resistance; and echocardiography in 11-15 year old individuals; 3) to repeat these measurements when the participants are 13-17 years old. These data will be used to address the hypotheses that 1) in early adolescence and prior to the onset of hypertension, insulin resistance is positively associated with systolic and diastolic blood pressure, forearm vascular resistance, left ventricular wall thickness, and plasma lipids; 2) during adolescence insulin resistance at baseline and/or changes in insulin resistance will predict changes in systolic and diastolic blood pressure and will be associated with changes in skinfold thickness, body mass index, waist/hip ratio and lipids; 3) changes in insulin resistance will be correlated with changes in forearm vascular resistance such that either an increase in insulin resistance predates changes in the peripheral vasculature and insulin resistance at baseline will predict changes in forearm vascular resistance or changes in the peripheral vasculature predate an increase in insulin resistance, and forearm vascular resistance at baseline will predict degree of insulin resistance; 4) changes in insulin resistance during adolescence will be associated with changes in left ventricular size. The participants for this study will be recruited after school blood pressure screening. The enriched population, with 50% of participants from the upper 15% of the blood pressure distribution, is used because they are most likely to develop high blood pressure to have the greatest rise of blood pressure over time. Studies will be conducted in a clinic setting and clinical research center. Forearm vascular resistance will be measured during ischemic exercise to determine maximal forearm blood flow and minimum forearm vascular resistance. Insulin resistance will be determined during euglycemic insulin clamp studies. Echocardiograms will be obtained using 2D-Echoguided M-mode imaging with Doppler to assess left ventricular measurements and total peripheral resistance.